This application claims the benefit of Korean Application No. 2002-11317, filed Mar. 4, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates in general to a valve, and more particularly, to a micro lock valve which maintains a normally closed state or a normally open state without consuming a large amount of electric power and is driven by low electric power for a long period of time.
2. Description of the Related Art
Generally, a pneumatic system is used in an automation system of an industrial field, a door of a bus or a subway, an air brake system of various vehicles, an air curtain of a department store or a refrigerator, pneumatic tools of an auto repair shop, etc. In the pneumatic system, air is compressed by a compressor and supplied to an actuator. The pressure due to the compressed air is converted into mechanical work.
The pneumatic system includes a pneumatic generator, an air cleaner, a pipe, a control valve, a driving device, and fittings. A directional control valve as the control valve is employed to change a flowing direction of air supplied to the actuator so as to control the actuator, and an electric valve is generally provided as the directional control valve. Herein, the electric valve is a general name given to a valve which is incorporated with an electromagnet and operated depending upon the electromagnet, and is also generally called a solenoid valve.
If the pneumatic system is applied to a small-sized machine, a miniature actuator and a controller to control the miniature actuator are combined, and the controller is driven by low electric power for a long period of time. However, the conventional solenoid valve consumes much of the electric power (e.g., about 0.5 W of electric power), in spite of the small-sized machine. Further, the pneumatic system generally needs a plurality of valves and thus, the electric power is consumed in proportion to the number of solenoid valves which should be simultaneously controlled.
Moreover, the electric power is continuously consumed even when the solenoid valve is in a normally closed state or a normally open state. Therefore, power consumption of the solenoid valve may be too much to form a small-sized pneumatic system.
Further, because the solenoid valve cannot maintain the normally closed state or the normally open state without consuming a large amount of electric power, when the supply of the electric power is cut off, the solenoid valve is loosened and a plunger in a cylinder of the pneumatic system is rapidly moved, thereby making a noise.
Accordingly, it is an object of the present invention to provide a micro lock valve which maintains a normally closed state and a normally open state without consuming a large amount of electric power and is driven by low electric power for a long period of time.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and other objects of the present invention are achieved by providing a micro lock valve including a cylinder forming an air chamber. One part of the cylinder is provided with an inlet port and an outlet port which communicate with each other through the air chamber, and the other part is provided with an exhaust port communicating with the air chamber. The micro lock valve also includes a plunger slidingly traveling in the cylinder, blocking up one of the inlet port or the exhaust port, and formed with a female screw thread in a traveling direction of the plunger. Further, the micro lock valve includes a driving shaft having a male screw thread mating with the female screw thread and a driving motor rotating the driving shaft forwardly and backwardly.
According to an aspect of the invention, the plunger is formed with a communicating hole through which the outlet port and the air chamber communicate with each other while the inlet port is blocked up by the plunger.
According to an aspect of the invention, the inlet port and the outlet port are provided in one side of the cylinder in parallel with a longitudinal direction of the cylinder, and the exhaust port is radially bored through the other side of the cylinder.
According to another aspect of the invention, the plunger and the cylinder have a noncircular cross section.
According to another aspect of the invention, the plunger and the cylinder have a circular cross section, and combined by a key to be prevented from rotating.
According to yet another aspect of the invention, the micro lock valve further includes a partition wall provided between the air chamber and the exhaust port, having an air passage being passed by the driving shaft, and an O-ring combined to the plunger and sealing the air passage.